Publications

Summary:
In this research we consider an approach for improving the efficiency and tightness of column generation (CG) methods for solving vehicle routing problems. This work builds upon recent work on Local Area (LA) routes. LA routes rely on pre-computing (prior to any call to pricing during CG) the lowest cost elementary sub-route (called an LA arc) for each tuple consisting of the following: (1) a customer to begin the LA arc, (2) a customer to end the LA arc, which...

Summary:
At the core of any flight schedule is the four dimensional (4D) trajectories which are comprised of three spatial dimensions with time added as the fourth dimension. Each trajectory contains spatial and temporal features that are associated with uncertainties that make the prediction process complex. Because of the increasing demand for air transportation, airports and airlines must have optimized schedules to best use the airports’ infrastructure potential.

Summary:
In this research we consider an approach for improving the efficiency and tightness of column generation (CG) methods for solving vehicle routing problems. This work builds upon recent work on Local Area (LA) routes. LA routes rely on pre-computing (prior to any call to pricing during CG) the lowest cost elementary sub-route (called an LA arc) for each tuple consisting of the following: (1) a customer to begin the LA arc, (2) a customer to end the LA arc, which...

Summary:
Green loading zones (GLZs) are curb spaces dedicated to the use of electric or alternative fuel (“green”) delivery vehicles. Some US cities have begun piloting GLZs to incentivize companies to purchase and operate more green vehicles. However, there are several questions to be answered prior to a GLZ implementation, including siting, potential users, and their willing to pay.

Summary:
At the time we are writing this article, hundreds of thousands of delivery vehicles are getting ready to hit the road and travel across U.S. cities to meet the highest peak of demand for ecommerce deliveries during Thanksgiving, Black Friday, and the Christmas holiday season. This mammoth fleet will not only add vehicle miles traveled through urban centers but also increase parking congestion, battling with other vehicles for available curb space.

Summary:
Fundamental diagrams describe the relationship between speed, flow, and density for some roadway (or set of roadway) configuration(s). These diagrams typically do not reflect, however, information on how speed-flow relationships change as a function of exogenous variables such as curb configuration, weather or other exogenous, contextual information.

Summary:
While the number of deliveries has been increasing rapidly, infrastructure such as parking and building configurations has changed less quickly, given limited space and funds. This may lead to an imbalance between supply and demand, preventing the current resources from meeting the future needs of urban freight activities. This study aimed to discover the future delivery rates that would overflow the current delivery systems and find the optimal number of resources.

Summary:
West Seattle (WS) is a part of the city of Seattle, Washington, but is located on a peninsula west of the Duwamish River. The West Seattle High-Rise Bridge serves as the primary connector between West Seattle and the rest of the city, carrying some 84,000 vehicles on average each day. On March 23, 2020, that high bridge was suddenly closed to all vehicle traffic for safety reasons due to greater-than-expected structural deterioration. The high bridge is now being repaired with a...

Summary:
While several stakeholders in the private and public sectors are taking actions and drafting roadmaps to achieve sustainable urban freight goals, the urban freight ecosystem is a complex network of stakeholders, achieving such sustainability goals requires the collaboration and coordination between multiple agents. Researchers collected and synthesized views from both the private and public sectors on what is needed to sustainably deliver the last mile and identify roadblocks towards this goal.

Summary:
Common-carrier parcel lockers have emerged as a secure, automated, self-service means of delivery consolidation in congested urban areas, which are believed to mitigate last-mile delivery challenges by reducing out-of-vehicle delivery times and consequently vehicle dwell times at the curb. However, little research exists to empirically demonstrate the environmental and efficiency gains from this technology.

Summary:
Cities need new load/unload space concepts to efficiently move freight, particularly as autonomous vehicles (both passenger and freight) become feasible. This research aims to: understand the importance of off-street commercial parking, understand how off-street facilities are managed, and determine whether off-street commercial parking is an underutilized resource for urban goods delivery.

Summary:
Micro-consolidation implementations and pairing with soft transportation modes offer practical, economic, environmental, and cultural benefits. Early implementations of micro consolidation practices were tested but cities need to understand their implications in terms of efficiency and sustainability. This study includes a research scan and proposes a typology of micro-consolidation practices.

Summary:
Parking cruising is a well-known phenomenon in passenger transportation, and a significant source of congestion and pollution in urban areas. While urban commercial vehicles are known to travel longer distances and to stop more frequently than passenger vehicles, little is known about their parking cruising behavior, nor how parking infrastructure affects such behavior.

Summary:
The rapid rise of on-demand transportation and e-commerce goods deliveries, as well as increased cycling rates and transit use, are increasing demand for curb space. This demand has resulted in competition among modes, failed goods deliveries, roadway and curbside congestion, and illegal parking. This research increases our understanding of existing curb usage and provides new solutions to officials, planners, and engineers responsible for managing this scarce resource in the future.